The National Institutes of Health (NIH) estimate that over 500,000 annual hospital admissions for heart failure patients are avoidable. Heart failure is a tremendous problem in the United States that affects millions of people and costs billions of health care dollars each year. A number of tests allow a doctor to assess heart function; however, proper implementation of many of these tests requires expensive equipment and/or a qualified professional. This makes it difficult and expensive to monitor the condition of a patient, as the patient must routinely visit the hospital or risk late detection of a worsening heart condition.
These troubling numbers have led researchers and companies to improve the methods for monitoring heart failure outpatients with the goal of reducing unnecessary hospital readmissions and costs. One proposed solution transmits a patient's body weight measured on a bathroom scale to his/her physician because increasing body weight could be a sign of fluid retention, which might result from a worsening heart condition. Such diagnostic mechanisms are, however, less than ideal. Body weight can be affected by factors other than fluid retention, and fluid retention can be caused by factors other than heart conditions. Thus, such techniques result in false positives, or worse, fail to detect worsening heart conditions.
The ballistocardiogram (BCG) is a non-invasive diagnostic technique which measures the mechanical recoil of the body in reaction to the ejection of blood from the heart through the vasculature. BCG measurement methods were developed in the mid-1900s and largely abandoned in the early 1960s due to impracticality and unreliability. Reliable and practical BCG signal acquisition would provide an excellent tool for evaluating a patient's cardiovascular health. However, such signal acquisition remains challenging for use in a variety of applications.